Epigenetic Mechanisms as Drivers of Environmental Responses in Stony Corals

The current pace of anthropogenic global change is imposing unprecedented conditions to biological systems. Coral reef ecosystems are particularly sensitive to the rapid increase in thermal anomalies and the changes in water chemistry caused by global change. However, although their decline has been documented worldwide, there are signs suggesting that stony corals harbor greater phenotypic plasticity than previously expected, sparking the interest in the study acquired non-genetic modifications (e.g., epigenome, microbiome) potentially increasing their resilience to global change, and constituting one of the main targets for intervention. Epigenetics constitutes an exciting frontier to understand how the environment influences the regulation of the expression of genetic information and modulates phenotypic variation. This has the potential to change the way we understand short-term acclimation and adaptation to a changing environment, aiding to improve predictive models of ecosystemic persistence under current and future climatic scenarios. However, while there is evidence supporting the idea of epigenetic mechanisms participating in rapid-response acclimatization, specific details about how this process is influenced by specific environmental conditions are lacking. In non-model organisms, we often lack information about the presence and functionality of some of these mechanisms, limiting the application of epigenetics in the study of ecosystem resilience in response to global change. This dissertation aims to elucidate how epigenetic mechanisms contribute to coral phenotypic responses to the effects of global change in the oceans. For that purpose, hypotheses about the presence and responsiveness of different epigenetic mechanisms in corals, its interaction with the genome and microbial communities, as well as its role modulating gene expression and phenotypic responses to diverse stressors were explored. Histone repertoires and/or full methylomes were characterized for the first time in the corals Acropora cervicornis and Montastraea cavernosa. The participation of these epigenetic mechanisms modulating responses to nutrient contamination, seasonal environmental change, thermal stress and acidification was demonstrated, providing evidence supporting its participation in intragenerational plasticity. A conserved seasonal methylation program was observed in A. cervicornis. This together with the strong influence of the genome over DNA methylation evidence its heritability and its potential to participate in intergenerational plasticit

Chitosan coating surface and permeation properties as affected by plasticizer, surfactant and polymer concentration-application to vegetables

Edible coatings can act as moisture, lipid, and gas barriers and can improve the textural properties of foods or serve as carriers of functional agents such as colors, flavors, antioxidants, nutrients and antimicrobials. The objectives of this work were to study the potentialities of chitosan (obtained from lobster of the cuban coasts) coating to extend the shelf life of fruits. To do so, the surface properties of tomato and carrot were characterized and the wettability properties of chitosan edible coatings were studied. In such coatings, parameters such as chitosan concentration and effects of type and concentration of hydrophilic plasticizer or surfactant on wettability of chitosan coatings were evaluated, as well as the respective barriers properties to gases. It was possible to determine the values of the polar and dispersive components of the superficial tension, that are 3.32 and 25.24 mN/m, respectively, for the tomato and 0.48 and 25.62 mN/m, respectively, for the carrot; being the superficial tensions of the tomato and carrot the sum of the two components (28.55 and 26.40 mN/m) respectively. Both are therefore, low energy surfaces. The results of wettability determinations allowed to adjust one factorial model that suggests an increase of the spreading coefficient as the chitosan concentration decreases and Tween concentration increases. The best values of wettability correspond to the following coating composition: 1.5 % (w/v) of chitosan and 0.1 % (w/w) of Tween 80. A correlation has been found between the water vapor, oxygen and carbon dioxide permeability coefficients, and glycerol concentration (while keeping Tween and chitosan concentrations constant). In the absence of glycerol, a decreased permeability to the gases was observed. An increase of the chitosan concentration decreases a lightness and increase yellow color of coatings. The chitosan coatings with glycerol showed high values lightness and were more transparent and yellowier than those without glycerol

Chitosan coating surface properties as affected by plasticizer, surfactant and polymer concentrations in relation to the surface properties of tomato and carrot

The objectives of this work were to determine the effects of the concentrations of glycerol and sorbitol (as hydrophilic plasticizers), Tween 80 (as surfactant) and chitosan on the wettability of Cuban chitosan-based edible coatings in view of their application on tomato and carrot and to develop a model allowing the optimization of coating composition. The values of the polar and dispersive components of the superficial tension of the foods were determined to be 3.04 and 25.67 mN/m, respectively, for tomato, and 0.34 and 26.13 mN/m, respectively, for carrot, the sum of the two components being the superficial tensions of tomato and carrot (28.71 and 26.48 mN/m, respectively). The skins of both foods are therefore low-energy surfaces, meaning that the Zisman method for the determination of wettability could be applied. The best experimental values of wettability were obtained for the following coating composition: 1.5% (w/v) of chitosan and 0.1% (w/w) of Tween 80. The increase in the concentration of chitosan and glycerol or sorbitol as plasticizers decreased the values of wettability and adhesion coefficients. The results of wettability were adjusted to a polynomial model that describes the dependence of the adhesion coefficient (Wa), cohesion coefficient (Wc) and spreading coefficient (Ws) on chitosan and Tween 80 concentrations. The optima calculated by the model equations were in excellent agreement (relative error below 3%) with the experimental values.Coordenação Aperfeicoamento de Pessoal de Nível Superior (CAPES, Brazil).aLFA VALNATURA Project of Europe Aid Cooperation Office

Chitosan coating and films : evaluation of surface, permeation, mechanical and thermal propertiess

The potentialities of chitosan (from lobster of the cuban coasts) coating to extend the shelf life of vegetables were evaluated. To do so, the surface properties of tomato and carrot were characterized and the wettability properties of chitosan coatings were studied. In such coatings, chitosan concentration and effects of type and concentration of plasticizer or surfactant on wettability of chitosan coatings were evaluated, as well as the respective barrier and mechanical properties. Additionally, a blend of chitosan and clay microparticles was performed and the films obtained were characterized in terms of barrier, mechanical and thermal properties. The values of the polar and dispersive components of the superficial tension for the tomato and the carrot were determined, being the superficial tensions of the tomato and carrot 28.55 and 26.40 mN/m, respectively. The results of wettability determinations allowed the construction of one factorial model. The best values of wettability correspond to the following coating composition: 1.5 % (w/v) of chitosan and 0.1 % (w/w) of Tween 80. Acorrelation has been found between the gas permeability coefficients and chitosan concentration (while keeping Tween concentrations constant). The water vapour barrier property of the chitosan films was significantly improved by incorporation of clay, the tensile strength increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. The obtained models are meant to predict the properties of chitosan/clay films to be prepared.Las potencialidades del empleo de coberturas de quitosana (obtenida a partir de langosta) para extender la vida de anaquel de los vegetales fueron evaluadas. En este sentido fueron determinadas las propiedades de superficie del tomate y la zanahoria y el efecto de la concentración de polímero, tipo y concentración de plastificante, así como la concentración de agente surfactante sobre la humectabi-lidad de las coberturas de quitosana. Las coberturas que mostraron mejor humectabilidad fueron ca-racterizadas en relación a sus propiedades de barrera y mecánicas. Adicionalmente fueron obtenidas películas de quitosana/arcilla y caracterizadas sus propiedades de barrera, mecánicas y térmicas Los valores de las componentes polar y dispersiva de la tensión superficial del tomate y la zanahoria fueron determinados, siendo la tensión superficial de los mismos 28.55 y 26.40 mN/m, respectivamente. Los resultados de las determinaciones de humectabilidad se ajustaron a un modelo factorial. Los mejores valores en términos de humectabilidad correspondieron a la cobertura con una composición de: quitosana 1.5% (m/v) y 0.1 % (m/v) de Tween 80. Una incidencia de la concentración de quitosana (concentración de Tween constante) sobre las propiedades mecánicas y de barreras de las coberturas fue encontrada. La permeabilidad al vapor de agua de las películas de quitosana fue significativamente mejorada con la adición de arcilla en su composición. El esfuerzo tensil aumentó significativamente con el aumento de la concentración de quitosana y arcilla, mientras que la elongación disminuyó ligeramente. Los modelos obtenidos permiten predecir las propiedades de las películas de quitosana/arcilla que se quie-ran preparar

Effect of moderate electric field in the physical and transport properties of chitosan coatings

Edible films and coatings can provide additional protection for food, while being a fully biodegradable, environmentally friendly packaging system. Preliminary works have shown that the presence of a moderate electric field during the preparation of chitosan coating solutions may influence e.g. their transport properties. The aim of this work was to determine the effect of field strength on functional properties of chitosan coatings (obtained from lobster of the Cuban coasts). Four different field strengths (50,100,150, 200 V·cm-1) were applied during the preparation of the film forming solution, films were cast and, for each electric treatment, the water vapor, O2 and CO2 permeabilities of the films were determined, together with their solubility in water. The films were also analysed using scanning electron microscopy (SEM) and X-ray diffractometry (XRD).The results showed that the electric field has statistically significant effects on films transport properties (which e.g. for water vapour permeability, varied from 0.3228 to 0.2667(g.(m.day.atm)-1)) and structure, a positive correlation having been found between the water vapor, O2 and CO2 permeability coefficients and the applied field strength. XRD indicated that when electrically treated, chitosan films exhibited a more ordered structure and a clearly higher crystallinity when compared with non-treated films. SEM micrographs evidenced that the surface morphologies of chitosan films were influenced by the electric field. In fact, the electric field treatment led to a structure with more regular layers as can be seen in the cross-sections of the films. These results clearly indicate that, when applied to the film-forming solution, the electrical field treatment may be a good tool to finely adjust the transport properties e.g. in taylor-made film formulations

Influence of electric fields on the structure of chitosan edible coatings

The aim of this work was to evaluate the effect of electric fields applied at different field strength values on mechanical and thermal properties of chitosan films/coatings (obtained from lobster of the Cuban coasts). XRD analyses indicated that electrically treated chitosan films exhibited a more ordered structure and a clearly higher crystallinity when compared with non-treated films, thus displaying significant effects on the value of the crystallinity index (CI). SEM micrographs evidenced that the surface morphology of chitosan films was influenced by the electric field. In fact, the electric field treatment led to a structure with more regular layers as can be seen in the cross-sections of the films observed under SEM. The application of the electric field to chitosan film-forming solutions resulted in an increase of the tensile strength (c.a. 9%) and elongation-at-break (c.a. 18%) of the corresponding chitosan films. The reported results demonstrate that the application of an electric field to film-forming solutions of chitosan is an interesting instrument to taylor relevant properties of the films or coatings produced from them.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES Brazil)Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/23897/2005, RH/BD/32566/200

Effect of moderate electric fields in the permeation properties of chitosan coatings

Edible films and coatings can provide additional protection for food, while being a fully biodegradable, environmentally friendly packaging system. Preliminary works have shown that the presence of a moderate electric field during the preparation of chitosan coating solutions may influence e.g. their transport properties. If such effect is confirmed, moderate electric fields could be used to tailor edible films and coatings for specific applications. The aim of this work was to determine the effect of field strength on functional properties of chitosan coatings (obtained from lobster from the Cuban coasts). Four different field strengths were tested (50, 100, 150, 200 V cm−1) and, for each electric field treatment, the water vapor, oxygen and carbon dioxide permeabilities of the films formed were determined, together with their color, opacity and solubility in water. The surface microstructure of the films was analyzed using atomic force microscopy (AFM). The results showed that ohmic heating had statistically significant effects on film's physical properties and structure. In general, the most pronounced effect of the field strength was observed for treatments made at 100 V cm−1 or higher, a positive correlation being found between the water vapor, oxygen and carbon dioxide permeability coefficients and field strength. The AFM results show that the surface of chitosan films is much more uniform when an electric field is applied, which may be related with a more uniform gel structure leading to the differences observed in terms of transport properties.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Europe Aid Cooperation Office - αLFA VALNATURA ProjectFundação para a Ciência e a Tecnologia (FCT

Effect of chitosan-based coatings on the shelf life of Salmon (Salmo salar)

This study aimed at determining the effect of chitosan coating on shelf life extension of salmon (Salmo salar) fillets. The success of edible coatings depends highly on their effective wetting capacity of the surfaces on which they are applied. In this context in a first stage the surface properties of salmon fillets and the wetting capacity of the coatings on fish were evaluated. In terms of wettability there were no significant differences (p > 0.05) between the solutions presenting higher values (solutions 1−4); therefore, solution 1 with a spreading coefficient (Ws) of −4.73 mN m−1, was chosen to be subsequently analyzed and applied on fish fillets. For shelf life analyses the fillets were coated and stored at 0 °C for 18 days. The control and coated fish samples were analyzed periodically for total aerobic plate count (TPC), pH, total volatile base nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric acid (TBA), and ATP breakdown products (K value). The results showed that fish samples coated with chitosan presented a significant reduction (p < 0.05) for pH and K value after 6 days and for TVB, TMA, and TBA values after 9 days of storage, when compared to control samples. In terms of microbial growth, a slower increase in TPC was observed for the coated fish, indicating that chitosan-based coatings were effective in extending for an additional 3 days the shelf life of the salmon. These results demonstrate that chitosan-based coatings may be an alternative for extending the shelf life of salmon fillets during storage at 0 °C.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil); Fundação para a Ciência e a Tecnologia (FCT, Portugal); ALBAN-European Union Programme of High Level Scholarships for Latin America

Chitosan/clay films' properties as affected by biopolymer and clay micro/nanoparticles' concentrations

Blends of chitosan (from Cuban lobster) and clay micro/nanoparticles were prepared by dispersion of the clay particles in the film matrix and the films obtained were characterized in terms of water solubility, water vapor, oxygen and carbon dioxide permeability, optical, mechanical and thermal properties using an Instron universal testing machine, differential scanning calorimetry, thermogravimetric analyses and scanning electron microscopy (SEM). The water vapor barrier properties of the films were significantly improved by incorporation of clay in their composition, while the water solubility decreased as the clay concentration increased (for a constant chitosan concentration). The tensile strength of chitosan/clay films increased significantly with increasing chitosan and clay concentrations, while the values of elongation decreased slightly for high values of chitosan concentration. Tm increased with the increase of chitosan concentration, but the changes in Tm with the addition of clay were not significant. Polynomial models were fitted to the experimental data in order to facilitate future design of chitosan/clay film systems.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Brazil)Fundação para a Ciência e a Tecnologia (FCT)αLFA VALNATURA Project of Europe Aid Cooperation Offic

In Vivo Confirmation of the Role of Statins in Reducing Nitric Oxide and C-Reactive Protein Levels in Peripheral Arterial Disease

AbstractObjectivesInflammatory and other processes mediating impairment of endothelial function, where there are increased levels of C-reactive protein (CRP) and plasma nitrites, have a part to play in the early stages of peripheral arterial disease (PAD). Our objective was to analyse the effect of statins on the plasma nitrite and CRP levels in PAD.Material and methodsA prospective study of 30 patients with PAD Fontaine stage II, with no prior treatment with statins, determined high sensitivity (hs)-CRP and lipid profile in the patients. Plasma nitrite levels were determined by colourimetric assay based on the Griess reaction, at baseline and after 1 month of treatment with atorvastatin 40mgday−1.ResultsA significant reduction in plasma nitrite levels was detected after the treatment with statins (11.88±7.8μM vs. 5.7±1.8μM, p=0.0001). There was also a significant reduction in hs-CRP levels (13.58±24.00 vs. 3.93±3.19, p=0.02).When the patients were stratified according to claudication stage, a significant reduction in nitrite levels was obtained, both in patients with PAD Fontaine stage IIA (9.5±3.3μM vs. 5.3±1.7μM, p=0.0001) and in stage IIB (16.6±11.6μM vs. 6.7±1.8μM, p=0.032).ConclusionsTreatment with statins lowers plasma nitrite and CRP levels in patients with PAD. Our data support the effects of statins in vivo that have been demonstrated on the endothelium ex vivo, suggesting a beneficial effect by acting on the initial processes that trigger the disease, reducing oxidative stress (increase in the bioavailability of nitric oxide as peroxynitrite levels decrease) and curtailing the inflammatory processes which perpetuate the disease